Centrifugal fan.



W. J. BALDWIN.

' GBNTBIFUGLL PAN. APPLUJATION FILED JULY 7. 1 906.

898,624.' l' I Patenteasept. 1 5, 190,3.

lvl-Tucson l V @kada eanlmaun M PATENT oFF-ICE.

WILLIAM J. BALDwiN, or BnooiiLrN` Qyiw vom,

.CENTRIFUGAL FAIL Specification of Letters Patent.

Patented Sept. 15, 1908.

Application tiled July 7, 1906. Serial No. 325.064.

To all tch om it may concern:

Be it known that W'ILLIAM J. BALDWIN,

a citizen ofthe United States of America, and a resident'of the borough of Brooklyn, 2

in the countyof Kings, State of New York, have invented certain new and useful Improvements in Centrifugal Fans, of which the following is a specification.

This invention relates to improvements in centrifugal fans' or blowers, and it particularly pertains, but is not restricted to. improvements in installations of centrifugal fans ofthe particular type known as A"forward direction fans.- L

The invention essentially relates to the combination of a plurality of such fans, arranged tandem Within a casing, and the purpose and effect of the invention is to materially increase the pressure of the air deliivered by such an installation over that which could be attained by a sinel'e fan. I have determined that when a plurality Ofsuch fans are set tandem in a'casing, so that `the air delivered by the first-fan goes practically directly to the inlet of the next fan, from that fanto the inlet of the third fan, if athird is used, and so on, the pressure of the delivered air rises in some function of 'the number of the fans employed, and with forward-direction fans this is nearly in proporf f tion to thenumber of the ,'fans. Therefore,

- by thisA invention it becomes possible to produce comparatively small compact blowing apparatus capable of delivering air at great pressures andconsequently capable of forcing 1t agamst conslderable'resistances, thereby filling a Want in variousmodern arts, as'

in certain branches of electrical engineering. Referring to the drawings which acco1`npany the speciiication to aid the description, Figure 1 is a longitudinal section, partly in elevation, of an installation containing three forward direction fans, Fig. 2 is a cross section on the line 2. of Fig. 1. I

In a casing of a cylindrical section and somewhat larger diameter than the fans, are arranged tandem a plurality of centrifugal fans, preferably of the forward direction type. The said casing ay may heconstructed' as a single shell or may be madein sections fastened together, and in the latter case the joints would naturally be at labout the oints a: 'y' at the apexes of the plates h, i. The drawings show the said fans as substantially similar to that set forth in my United States Patent No. 556,453, dated March 17,

f 1896.-; being a shell, c a cone fixed on a i shaft g driven in any manner, as by pulley and belt l, and hladesf extending between Iand secured to said shell d and cone e. The air coming in through the open rear end of casing a enters at the small and open rea-r of the blades f. together with shell d and cone e, is given an outward and forward diflected by the contracted throat plate 7L inwardly to the inlet of the next-similar fan. Said contracted throat plate h is preferably of conical shape and is fastened to said casing u; and in order to force the air into the inlet of said next fan and to prevent its impinging on the periphery of the shell thereof, Lprefer to employ a backing "t immediately behind and conforming to the shape of the shellnof said fan, and of course said throat plates z and backing t' may be either of sheet metal as indicated, or solid castings or forgings. Y

Theother fans are preferably of the saine size, shape and type as said first fan, and are, as hereinbefore stated, arranged tandem, i that is in front of one another and concentric to said casing a, and.between each pair of fans is a contracted throat plate to direct the air coming from one fan into the inlet of the next forward fan. I also prefer to fix all the I fansl on the saine shaft g, supported in bearing on arms m .in casing (l, and which is driven in any suitable manner, as by pulley 7c and belt hut it is evident that the several fans might be placed each on its separate shaft, and l might alsoarrange the fans with alternately opposite pitch and drive them in opposite diret-tions. instead of giving all the fans the saine blade pitch and driving them all inthe saine, direction. `\v or is there any limit to the number of fans employed, it be-` ing practicableto employ two or anygreater number.

The air enters at the inlet end of casing a, acquires a certain forward velocity and presters the second fan with this velocity and pressure, gains a greater forward ressure while passing through the second an, and so on, finally escaping from the open front end of casing a with a materially greater forfan.

I claim as my invention.

i end of shell (I, and by the `centrifugal"effect` rection against said casing a, then being de-A sure while passing through theiirst fan, en-v Ward pressurev than it received at the first- NOW. having described my improvements,

I f-'lhe combination of-a casing, a plu-A i '4898,6'24 i 'i 3,. The combination of a casing open at u llality offfoiiward direction fansarranged tanvboth ends, a vplurality vof forward direction fdex'n therein, andthroatsh' between each pair of fansv inclined inwardly and forwardly 1 5V 'to direct' the air from the rearward fan into the center of the forward fan, substantially asdescribed. l

2. The combination of a casing open at both ends, a plurality of forward. direction 1o fans'arranged tandem therein, and inclined .throat plates h and backing plates i between each pair of fansA adaptedvto direct the air from a rearward fan into the center of'a forcurrents, subi 'l ward-fan and to prevent back 15 stantially as described.

lfans therein' 'each having a conical closed center 'e 4and a conical shell d with open center, and inclined throat plates h and backing 2o plates/ between each pan' of fans adapted to direct the air from a rearward fan into the open center of'a forward fan and prevent back currents, substantially as described.

Signed at yNew York city this 5th day of 25 July 1906.. 4 1 f V vWILLIAM'J. BALDWIN Witnesses :lr y l HENRY HQDE Vos, DAVID' W. BROWN. 

